Вырастут до 30-40см(2,5-3года) тогда жди нереста...если получится...самец стройнее- самка толстее...

Comparison of the genital papilla in mature fish shows the differences in the sexes to the trained eye. In males this is a small yet thick stump which noticeably protrudes from the fish's undercarriage. In females it is less obvious and is recessed or lies flat with the body.

A lot of people have made claims of eggs appearing, and if it is true; theyd never hatch due to the process that needs to be taken.
Sailfins take a year to breed (if you have a pair) 2 years minimum if theyve never met.
The size of the pond im not too sure on, but shouldnt be too hard to figure out using an approximation of 1cm:2L ratio plus double the length of an adult fish body. So the pond would need to be minimum 1m in diameter. Volume, not too sure about.

Now with the breeding, as i said it takes a full year. It's similar to replicating the environment when breeding peppermint bristle nose (the wet and dry seasons). The difference is, gibbys need their cycles to be done naturally by standard fluctuating weather conditions over a 12month period, where as peps can be achieved in a controlled environment. Trying to replicate the same environment can be significantly hard in an outdoor pond, BUT just like a lot of loricaridae, once they start, they can potentionally do it like clock work if weather conditions permit.

Im not too sure where gympie is in queensland, but i know the pleco farms are located in the northern most parts of queensland as to replicate the conditions in peru and brazil. The part of the amazon they are located sits approximately 15 degrees below the equator. In queensland australia, you'd be looking at cairns and above. Anything lower than townsville may be a lost cause.

Once you have a decent size pair with a sufficient volume of water that can maintain temperatures between 20 and 30 degrees on an annual basis, you can almost sit back and let it happen. Although ive heard of a decrease in production as we've had a winter in our summer this year. If ozone depletion slows donw a bit, you could have yourself up to 100 fry this time next year.

Now for the process - you need to take this into consideration when building the pond.
The male finds a secluded spot in the bank just below the surface of the water and waits for the female to join. The bank needs to have sufficient overhang as to allow little if any light in at all. The male will burrow quite deep into the riverbank making an underwater cavity, this will often be where the two retreat in the colder months. After which there will hopefully be a sudden increase in humidity and sunlight exposure to the pond which is when they will lay (usually in the spring months - september/october). The female will then leave the cavity and wont be very mobil for a few days. The male will stay here rolling the eggs for almost a month, after which he will close up the cavity with a thin layer of mud and sit over the top for upto 12 hours per day for about 2months. The eggs will remain in the riverbank incubating for this period with the male 'dusting' them gently with his anal fins. After hatching, he will keep them in the riverbank cavity for 4-10 days, after which they will be free swimming.